The present invention relates to intermediate yarn feeding devices of the type wherein yarn from a supply thereof is wound onto a storage member from which it is thereafter unwound and fed to a machine utilizing the yarn such as a textile producing machine or a sewing machine as demanded by said machine for demand feeding or at a predetermined linear rate for positive feeding.
More specifically, the storage member is generally in the shape of a drum with the yarn being wound tangentially about the drum at one end thereof forming a plurality of windings which advance axially toward the opposite end of the drum. Examples of storage drums of the type involved herein are shown in U.S. Pat. Nos. 3,225,446 and 3,737,112. In each case, the storage drum has an accumulating section which is generally cylindrical for the major part thereof and a loading section which may be conical or flared. The yarn is wound onto the drum at said loading section causing the first winding formed thereon to move axially onto the accumulating section which comprises the reduced diameter cylindrical portion of the drum and causing the next succeeding winding formed on the loading section to engage the preceding winding and displace the latter axially. The same process is repeated so that each newly formed winding axially displaces all the preceding windings on the storage drum.
Such prior art storage drum has not been entirely satisfactory for a number of reasons. More specifically, it has been found that in a number of instances, because of the particular profile of the storage drum, the point is reached where additional windings formed on the loading section, rather than axially advancing the precedingly formed windings forwardly toward the other end of the drum, accumulate rearwardly of the last formed winding and thus back-up on the loading section creating a serious problem of entanglement and preventing the formation of the intended single layer of turns of yarn on the drum.
Another problem often arising in conventional storage drums such as those referred to above is that the yarn initially engaging the loading section upon being wound thereon, rather than gradually sliding towards the last previously formed winding, literally jumps to such position.
It must also be recognized that in order for winding to take place upon the loading section of the drum, the yarn must be under some tension causing some elongation thereof. Further, the yarn is loaded onto the loading section, which has a greater diameter than the cylindrical accumulating portion of the storage drum so that as each winding moves from its loading section to the reduced diameter section, the initially elongated winding is partially restored to its unelongated form with resulting reduced tension. Such reduced tension reduces the frictional force opposing axial displacement of the yarn leading in turn to excessive looseness of the yarn windings and thus interferes with the uniform and controlled axial displacement of the windings on the storage drum.
The present invention has as its object the provision of a storage drum which eliminates the above pointed out drawbacks of the prior art storage drums.